docs: def rename(**kwargs):
    """Rename one or more columns, leaving other columns unchanged
  
    Example usage:
      diamonds >> rename(new_name=old_name)
    """
    def rename_columns(df):
      column_assignments = {old_name_later._name: new_name
                            for new_name, old_name_later in kwargs.items()}
      return df.rename(columns=column_assignments)
    return rename_columns